It is known that a toothbrush can be equipped with a treatment-force-measurement unit for determining when a treatment force with which a toothbrush head is pushed against the teeth reaches a predetermined treatment-force threshold value. Such a treatment-force-measurement unit may comprise a strain gauge sensor. It is also known that reaching the pre-determined treatment-force threshold value can be visually indicated. DE 34 146 23 C1 generally discusses such a toothbrush. The present disclosure provides a personal hygiene device having a novel treatment-force-measurement unit.